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Discussion Starter #1
Hi guys,

well last week I started car, and after 30 second, car change tone like it is running on 4 or 5 cylinders . After one minute car "repair" itself, and ran fine.
Yesterday I started car again, and it started nice, but again after 15-20seconds it change sound again, and it was heard like Subaru....and did not repair itself....
Well I unplug spark wires from coil, and found that on 3 and 6 cylinder there is no spark (first coil from front to rear ).

I had this same problem 7 years back, and change and tested PTU, Coils, wires, and finally I also send my ECU to AvPro for repair, and of course it was ECU. Car ran fine up to now. (car is 92 TT).
Now is it possible that is ECU again, or is PTU or Coil.... From my reading this forum I found some threads for not working 3 and 6 cylinder and always was ECU. Or am I wrong?

I just wanna get my car working again, before I do:
  • DR 750 swap
  • hotwire ignition coils
  • Spark plug cold 8
  • ARC 2+safc2 combo
  • Alu 2 piece drive shaft
  • Alcohol water injection
  • and tune again
 

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Well you will have to check all the wiring, from ECU to PTU signal, you can remove the CAS and rotate it by hand, with ignition ON and you should hear and see the injectors firing and spark plugs you can disconnect the injector plug so no fuel is spraying and diagnose the PTU/coilpack, I once used a set of LEDS connected to the 3v outputs from the ecu to PTU, that way I found that my ecu was sending the correct signal, it was a wiring problem with the coilpack.
 

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Hi guys,

well last week I started car, and after 30 second, car change tone like it is running on 4 or 5 cylinders . After one minute car "repair" itself, and ran fine.
Yesterday I started car again, and it started nice, but again after 15-20seconds it change sound again, and it was heard like Subaru....and did not repair itself....
Well I unplug spark wires from coil, and found that on 3 and 6 cylinder there is no spark (first coil from front to rear ).

I had this same problem 7 years back, and change and tested PTU, Coils, wires, and finally I also send my ECU to AvPro for repair, and of course it was ECU. Car ran fine up to now. (car is 92 TT).
Now is it possible that is ECU again, or is PTU or Coil.... From my reading this forum I found some threads for not working 3 and 6 cylinder and always was ECU. Or am I wrong?
You described the exact symptoms of a failing PTU. This exact same thing happened to me when my PTU started going out; it would intermittently stop sending the signal to one of the coil packs, which means you lose spark on 2 cylinders. Note, your tach should also read 4/6 of what the actual RPM is when this happens. I also got a CEL, which would disappear when the PTU "fixed itself".

Of course it could also be a coil or the ECU, but the intermittent nature and problem you described sound like PTU, so that should be the first check. You can easily remove and bench test the PTU, but make sure you do so when it is not working (if you test it after it has "fixed itself" it may bench test fine)
 

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Discussion Starter #4
I will bench test PTU to se what I get. Will post back... Should I heat it with fan a little bit, because I read somewhere, that when sensors are cold the give you one readings, but if you heat them, like when engine is running, you can get different numbers?
 

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If you don't find anything wrong with PTU, check the wiring harness between the PTU and the coil pack there's a yellow wire that splices into the 3-6 coil line, and a portion of it hangs out of the wiring loom.

Spent 9 months chasing an ignition issue like yours just to find out that wire had lost some insulation there and was shorting to the trans.

Sent from my SM-G892A using Tapatalk
 

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Discussion Starter #7
Ok guys,

Today I had finally some time for my Stealth.

I pulled Coils out and measure their resistance.
Primary Coil resistence (measure on connector)
Coil A (1-4 cylinder)= 0,8 Ohm
Coil B (2-5 cylinder)= 1,9 Ohm
Coil C (3-6 cylinder)= 1,9 Ohm


Secondary Coil resistence (measure between each coil on the top where cable connect)
My value is all three were12,7kOhm
Standard value is 11,3-15,3kOhm

I measure also my old Coils and had same results.

Well in the book it they say that standard value = 0,67-0,81 ohm.

So what do you guys think?

I need to measure also PTU but just dont know what to do with my multimeter (I have OHM, V and A on my multimeter), and dont know what should I use for measure continuity?) Help is apreciated :)
 

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Discussion Starter #9
Nope, because I know only one friend who has 93 TT but his car is apart, spun bearing.... I just really hope that my Ecu is ok, because it was already repair by AvPro years back
 

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Discussion Starter #10
Ok guys, I measure also PTU.

1-4 coil have 1,77mA and 43kOhm ( with 1,5V battery)
2-5 coil have 1,77mA and 43kOhm ( with 1,5V battery)
3-6 coil have 1,77mA and 43kOhm ( with 1,5V battery)

or should I check / measure anything else?

Is my PTU ok?
 

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Discussion Starter #11
IAs I mentionted in the first post, my car starts nice, but after few minutes, car start to run withou 3-6 coil. Of course there is heat under the hood.
Now I remebered this, and measure again with hairdrier on ptu. So after 2 minutes of heating this are results....

1-4 coil have 1,60mA and 43kOhm ( with 1,5V battery)
2-5 coil have 1,59mA and 43kOhm ( with 1,5V battery)
3-6 coil have 1,58mA and 43kOhm ( with 1,5V battery)

Any clue if this is normal or not?
 

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Discussion Starter #13
If you don't find anything wrong with PTU, check the wiring harness between the PTU and the coil pack there's a yellow wire that splices into the 3-6 coil line, and a portion of it hangs out of the wiring loom.

Spent 9 months chasing an ignition issue like yours just to find out that wire had lost some insulation there and was shorting to the trans

Sent from my SM-G892A using Tapatalk
Which yellow wire you mean? We have 3 connectors, 1 goes to coil (4 pin), then two connectors to PTU. Big and small connector(3pin).
I dont have any yellow wire there, just one with yellow stripe
 

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Which yellow wire you mean? We have 3 connectors, 1 goes to coil (4 pin), then two connectors to PTU. Big and small connector(3pin).
I dont have any yellow wire there, just one with yellow stripe
The 4 pin. It's kinda far down in the harness tho. You'll have to remove a few things to get to where it hangs out. Easy way to tell if that portion is stripped is just to check if the incoming line to the front most coil is shorted to ground

Sent from my SM-G892A using Tapatalk
 

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IAs I mentionted in the first post, my car starts nice, but after few minutes, car start to run withou 3-6 coil. Of course there is heat under the hood.
Now I remebered this, and measure again with hairdrier on ptu. So after 2 minutes of heating this are results....

1-4 coil have 1,60mA and 43kOhm ( with 1,5V battery)
2-5 coil have 1,59mA and 43kOhm ( with 1,5V battery)
3-6 coil have 1,58mA and 43kOhm ( with 1,5V battery)

Any clue if this is normal or not?
When you pulled the PTU to do the bench test, did you have a check engine light on? The PTU problem can be intermittent; you need to test it when the problem is occuring. It could bench test fine, then run fine for a bit, only to randomly drop a coil again later on. In my case, i drove the car until the CEL came back and i lost spark on one coil, pulled the PTU, and it bench tested bad on that coil.
 

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Discussion Starter #16
No because, I start doing on the car, while the cel was on, but I had to stop in the mean time because I had to do some other thing. So next mornig I start checking PTU.....
But I will order new PTU, because it is original on the car, that has never been changed. And I will report back.

Will check for wires too.
After that I will need to pull ECU, if that wont work.
 

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Your posts can be used as a diagnostic tool. Because it appears you are cycling between works, doesnt work. It mirrors the ptu cycle of failure. Because the ptu is only responsible for the absence or presence of the CONDUCTION of electricity, but NOT the AMOUNT of the electricity being conducted. This all/nothing 0/1 setup causes the part to have intermittent works/doesnt work symptom is normally described or qualified using terms like "going out, glitching out, dieing,etc"; but In reality as soon as a PTU starts to demonstrate the issue. Partial and intermittent functionality It is. Out dead Gonzo broken or irreparable Etc. Because just like the absolute on and off. Once BTU stops doing his job correctly. It's off Because it will never return to working correctly again. Based on what I've read at least. Where is with an ECU? Things just become progressively more. Problematic with all the different systems in the car itself because it controls so much more. Then just ones and zeros absolute on absolute us. So I just buy another PTU and install it. If you do not problems, then it's not the PTU but at least you know, you have a good PT you and you can eliminate that sometimes that's what it takes. . However absent ECU issues if you're having problem with spark, it's got to be the PTU. I say all this because I have just dealt with a misfire problem coil packs arcing Do various hoses in the engine bay? Non-firing cylinders or non firing spark plugs in the cylinders and a multitude of other electrical system related. Engine spark no spark Or even in some cases too much. Spark issues. You do not want to go The route I've been down. Trust me. I really believe that in my case anyway. A combination of fill PTU And bad coil or coils. Is causing the electrical arcing? Because a cracked coil behind a switch. That's just open or shut. Is going to have naughty habits. Which may even include throwing Spark? From itself to the nearest conductive object because energy like water, in the absence of some type of containment, Take the path. of least resistance. Mind you that is simply a hypothesis. But when one considers how much juice to coil packs release and combine that with a switch that stays open just a little bit too long Thus allowing more potential energy to be released from the coil That has a crack in its housing or an exposed area. Of metal for electricity to follow, and the amount of electricity is beyond the capacity of the wires to conduct effectively or more effectively than the crack in the housing. And say you've got added power. An easier path and I am pretty confident that that is what happened in my case and that can take out your ECU By the way. I would suggest simply stop messing with the PTU before you fry your ECU because your coils get to fatigued or get breached with a crack so now small price to pay man And again, then you know whether it's the PTU. Unless of course, it's faulty. Like coils did I purchased during this whole process of my problem solving. Good luck luck. Peace
 

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And I don't know how you were if we can edit our posts. So I'm just going to state that I am using talk and type. . And the contents of my previous post illustrate white one should never do official business with talk and type programs. LOL! And if you didn't understand what I was saying because of the frag words. Simply put I suggest the PTU is likely dead. If it's the problem it is dead. Buy a new PTU save yourself the of potentially frying an ECU or the frustrating time consumption required by having to Trace electrical traces LOL!
 

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And I don't know how you were if we can edit our posts. So I'm just going to state that I am using talk and type. . And the contents of my previous post illustrate white one should never do official business with talk and type programs. LOL! And if you didn't understand what I was saying because of the frag words. Simply put I suggest the PTU is likely dead. If it's the problem it is dead. Buy a new PTU save yourself the of potentially frying an ECU or the frustrating time consumption required by having to Trace electrical traces LOL!
He already posted that he replaced the PTU and it was the problem.
 
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